same here....I'm getting those fireball when I'm using my 3N38. I guess it's just pretty common with this powder. I've been using 3N37 now and I've eliminated those but I still like the 3N38 :-)
It happened to me also a while back. I used an old stock WIN SRP and somehow it cracked the primer, NO GO. It was hitting the edge of the primer so I replaced it and used the bent one, cut it and used it as my DF FP.